This invention relates to security tags and associated detachers and, more particularly, to a security tag and an associated detacher for use in an electronic article surveillance (EAS) system.
Electronic article surveillance systems are well known in the art and are used for inventory control and to prevent theft and similar unauthorized removal of articles from a controlled area. Typically, in such systems a system transmitter and a system receiver are used to establish a surveillance zone which must be traversed by any articles being removed from the controlled area.
An EAS tag is affixed to each article and includes a marker or sensor adapted to interact with a signal being transmitted by the system transmitter into the surveillance zone. This interaction causes a further signal to be established in the surveillance zone which further signal is received by the system receiver. Accordingly, upon movement of a tagged article through the surveillance zone, a signal will be received by the system receiver, identifying the unauthorized presence of the tagged article in the zone.
Certain types of EAS tags have been designed to be reusable and, thus, include releasable attachment devices for affixing the tags to the articles. Such attachment devices are further designed to be releasable by authorized personnel only so that unauthorized removal of a tag from its article is avoided. To this end, many attachment devices are made releasable only through the use of an associated special tool or detaching mechanism.
An EAS tag employing an attachment device and an associated detacher is described in U.S. Pat. No. 3,942,829, entitled REUSABLE SECURITY TAG, issued to Humble, et al. on Mar. 9, 1976 and assigned to same assignee hereof. The EAS tag of the '829 patent includes a tag body and an attachment device in the form of a tack assembly. The tack assembly includes an enlarged head and a tack body having a pointed end which serves to pierce through an article and to be receivable in and clamped to the tag body. This secures the article and tag together.
In the tag of the '829 patent, the tack is clamped to the tag body using a spring clamp formed as a clutch lock with spreadable jaws. Once the article is pierced, the pointed tack end is received in the tag body and is secured between the jaws of the clutch lock. This locks the tack and the tag body forming the EAS tag to the article so that the tag and article cannot be readily separated from each other.
In order for authorized personnel to be able to release the tack from the clutch lock and, therefore, the tag from the article, the '829 patent utilizes a detacher mechanism which is adapted to grip the tag body and apply a bending force thereto. This force is sufficient to deform the clutch lock so that the jaws of the clutch lock are spread apart, thereby releasing the tack. The tack can then be removed from the tag body so that the article and tag become separated from one another.
To permit the bending of the tag body sufficiently to deform the clutch lock, the tag body of the '829 patent must be made of a flexible material. Typically, flexible plastic materials such as, for example, polypropylene, have been used. Such materials, however, are susceptible to being cut and damaged. This tends to be a disadvantage, since it increases the likelihood that the locking feature of the tag can be separated from the EAS sensor part of the tag or can be exposed and defeated.
Moreover, the tag body of the '829 patent must be relatively large in size in order to facilitate its flexing. This likewise tends to be a disadvantage, since use of large tags detracts from the aesthetic appearance of the articles to which the tags are attached.
Another type of EAS security device is known in which a variation of the spring clamp of the '829 patent has been incorporated into a so-called keeper for a compact disc. This type of device is disclosed in U.S. Pat. No. 5,031,756, entitled KEEPER FOR COMPACT DISC PACKAGE OR THE LIKE, issued to Buzzard, et al. on Jul. 16, 1991 and also assigned to same assignee hereof.
The keeper of the '756 patent comprises a rigid plastic frame. One side of the frame is provided with an enlarged section which houses a tack-like button assembly and a spring clamp as in the '829 patent. In this case, the spring clamp is used to lock the button assembly in a first position. In this position, the pointed end of the button assembly protrudes into the frame to pierce and hold to the frame a cardboard container containing a compact disc. As a result, unauthorized removal of the compact disc with the frame causes an EAS sensor also incorporated into the frame, to generate a detectable signal for alarming an EAS system.
In the keeper of the '756 patent, the enlarged section of the frame is provided with opposing linear slots which lead to the region between the jaws of the spring clamp. By inserting ramped linear fingers into these slots, the fingers are guided into this region, causing the jaws to flex outward. This releases the button enabling it to be withdrawn from the cardboard container. The container and its housed compact disc can then be separated from the frame.
While the keeper of the '756 patent utilizes a spring clamp of the '829 patent type in a rigid frame, it also has certain drawbacks. One drawback is that the linear slots leading to the spring clamp permit in-line viewing and access to the clamp. This increases the susceptibility of the clamp to defeat, since linear objects can be inserted into the slots in an attempt to open the jaws. Another drawback is that the fingers of the detacher are required to be of high precision, since they must be received in the region between the spring clamp jaws. This increases the cost and complexity of the detacher.
It is, therefore, an object of the present invention to provide an EAS tag which does not suffer from the above disadvantages.
It is a further object of the present invention to provide an EAS tag having a hard tag body and which is adapted to be releasable from an article in an easy and simple manner.
It is also an object of the present invention to provide an EAS tag as set forth in the previous objectives and which is further adapted to be more difficult to defeat.
It is yet a further object of the present invention to provide a detacher for use in detaching the EAS tags set forth in the previous objectives.